1. Field of the Invention
The present invention relates to an illuminated push button unit. More specifically, the present invention relates to an illuminated push button unit in which light from a light source is emitted around a push-down control.
2. Background Information
A conventional illuminated push button unit is formed such that a light emission face is displaced along with a pushing down of a push-down control. With the illuminated push button unit, a light emission window that faces the light emission face is provided in an external housing of an electrical device in which the illuminated push button unit is mounted.
As shown in FIG. 6, the illuminated push button unit U includes a light-guide lens 1 and a lens holder 5. The light-guide lens 1 is made of a translucent resin. The light-guide lens 1 includes a light emission face 2 formed by a front end face of the light-guide lens 1. The light-guide lens 1 is affixed to the lens holder 5. The lens holder 5 is made of an opaque resin. The lens holder 5 is integrally provided with a light emission window 6, a push-down control 7, a hinge 8 and a switch pressing tab 9. The light emission window 6 faces the light emission face 2. The push-down control 7 is a protruding shaft.
With the illuminated push button unit U, the push-down control 7 is provided in a middle of the light emission window 6 of the lens holder 5. When the push-down control 7 is pushed in, the light-guide lens 1 is displaced along with the lens holder 5, with the hinge 8 as a fulcrum. When switching is performed by operation of a tact switch (not shown) by the switch pressing tab 9 of the lens holder 5, a light source such as an LED (not shown) is lit. The light from the LED is guided through the light-guide lens 1 to the light emission face 2. Then, the light exiting the light emission face 2 is emitted through the light emission window 6 of the lens holder 5.
As shown in FIG. 7, the lens holder 5 is integrally equipped with the push-down control 7 provided in the middle of the light emission window 6. To locate the push-down control 7 in the middle of the light emission window 6, the push-down control 7 is integrated with the lens holder 5 via short ribs 5a that extend inward from a plurality of places (two places in FIG. 7) around a periphery of the light emission window 6 of the lens holder 5.
Accordingly, with the illuminated push button unit U, the light emission window 6 ends up being partitioned into two small windows 6a by the ribs 5a at two locations. Therefore, even though the light is emitted circularly by the light emission face 2 of the light-guide lens 1, the ribs 5a create a shadow. As a result, the light is emitted discontinuously from the two small windows 6a of the light emission window 6. In other words, even though it is intended to obtain a ring of light by having a basic circular shape of the light emission window 6, and emitting light all the way around the push-down control 7, the ribs 5a end up creating a shadow. As a result, only arc-shaped light that is discontinuous between the small windows 6a is actually obtained. Thus, a completely continuous ring of light is not obtained.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved illuminated pushed button unit. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.